The age of the father 4 years ago was 5 times the age of his son. If the sum of their present ages is 44 years. What is the present age of his son?

Let the present age of father and son be x and y years respectively.
From 1st condition,
(x - 4) = 5(y- 4)
⇒ x - 4 = 5y - 20
⇒ x - 5y = -16 .....(i)
From 2nd condition,
⇒ x + y = 44 ...(ii)
From equation (i) and (ii)
-6y = -60
⇒ y = 10
∴ Present age of son = 10 years